Tomatoes

Daniel Barry for The New York Times

The tomato, though a fruit to botanists, has been decreed a vegetable by the United States Supreme Court. The verdict is not so unreasonable given that the tomato has a close cousin that is a vegetable, namely the potato.

The tomato, whose genome has been decoded, turns out to be one well-endowed vegetable, possessing 31,760 genes. This rich legacy, possibly a reflection of the disaster that killed off the dinosaurs, is some 7,000 more than a person, and presents a complex puzzle to scientists who hope to understand its secrets.

A consortium of plant geneticists from 14 countries spent nine years decoding the tomato genome in the hope of breeding better ones.

The scientists sequenced the genomes of both Heinz 1706, a variety used to make ketchup, and the tomato’s closest wild relative, Solanum pimpinellifolium, which lives in the highlands of Peru, where the tomato’s ancestors originated. The results were published in May 2012 in the journal Nature.

The tomato genome is both of intrinsic interest and a key to understanding the very versatile family of plants to which it belongs. The Solanum family, as it is known, includes the pepper, the tobacco plant, the potato, the eggplant and deadly nightshade.

That the tomato and potato contain so many genes does not mean that they are more sophisticated than people but that they have chosen a different stratagem for managing their cells’ affairs. Humans make heavy use of a technique called alternative splicing, which allows the components of each gene to be assembled in many different ways, so that one gene can produce many products.

The Solanum family, by contrast, has developed its genetic complexity through gaining more genes. About 70 million years ago, some lucky mishap in the process of cell division led to a triplication of the Solanum genome. The two spare copies of each gene were free to change through mutation. Many were useless and got dropped from the genome, but others developed useful new functions.

Usually, the triplication of a genome would be a considerable handicap, saddling a plant with three times as much DNA as it needs. But this event occurred around the time of the catastrophe in which the dinosaurs perished, and the extra genetic versatility may have been a lifesaver.

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July 30, 2014, Wednesday

Summer tomatoes are flourishing, and they go well with a wide variety of foods. Some can be used to make marinara sauce to get you through the winter, and the rest can be enjoyed raw and cooked in salads, sauces for everything from fish to vegetables...